Chemical Relationships Chemical Equations: Using shorthand to show balanced reactions by Robin Marks, M.A., Anthony Carpi, Ph.D. Reading Quiz Teach with this 1. What is a chemical equation? A way of calculating how many molecules are produced in a chemical reaction A shorthand representation of what happens in a chemical reaction A shorthand representation of the bonding in a molecule A method of comparing diatomic molecules. 2. What are the substances on the left side of a chemical equation called? Electrons Groups Products Reactants 3. What does the number in front of a molecular formula mean in a chemical equation? It shows that there is only one molecule present in a reaction It shows the number of reactions that took place It shows the number of that type of molecule involved in the reaction All of the choices 4. Can the subscripts in a chemical reaction be changed? Sometimes, depending on the energy released in the reaction Yes, to balance the equation Only for hydrogen, if there are water molecules on both sides of the reaction. o, the subscripts define the molecules in the reaction 5. Lavoisier observed that the mass of reactants is the same as the mass of the products after a reaction. Which of the following can you NOT conclude based on Lavosiers observation: The number of atoms in the reactants must be the same as the number of atoms in the products The number of molecules of reactant must be the same as the number of molecules of products No mass is lost or gained in the reaction The Law of Conservation of Mass 6. The law of definite proportions implies that: A chemical compound produced in a reaction will always have the same ratio of elements by mass, no matter what the source or amount of the reactants. Each particular chemical reaction produces substances with definite sizes and physical proportions The reactants in any chemical reaction will always create products in a one-to-one ratio In a chemical reaction, the ratio of product molecules will always equal the ratio of reactant molecules 7. What does it mean when a chemical equation is balanced? The equation represents equal weights of reactants and products The total of the coefficients (including those that equal 1) is the same on both sides of the equation There are the same number of molecules on either side of the equation There are equal numbers of each type of atom on both sides of the equation 8. What coefficient should be in front of the oxygen? 4 Al + __ O2 → 2 Al2O3 2 3 6 No number (the equivalent of the number 1) 9. What are the correct coefficients to balance this equation? 12 HClO4 + ___ P4O10 → ____ H3PO4 + _____Cl2O7 1, 4, and 6 2, 4, and 4 1, 6, and 8 2, 6, and 4 10. If you begin this reaction with 1 mole of Ba3N2 and 6 moles of HF, how many moles of each product do you get? Ba3N2 + 6 HF → ___ BaF2 + ___ NH3 1 and 1 6 and 6 3 and 2 3 and 6 Score Quiz
